Experimental determination of the effect and control of wood destroying fungi on alstonia boonei used for light engineering construction works

This research was carried out to experimentally determine the effect and control of wood destroying fungi on Alstonia boonei a soft wood used for light construction works. Five samples of Alstonia boonei labeled A, B, C, D and E and each of dimension 25mm x 300mm x 300mm were experimentally subjected to varying laboratory and environmental conditions. Samples A, B and C were exposed to moisture in a humid atmosphere for 20 days and it was observed that at the end of the 20th day, the weights of the samples appreciated, meaning that they had absorbed moisture from the surrounding atmosphere. Samples A, B and C were left for additional 40 days in the same humid atmosphere and it was observed that fungi spores had started to germinate on the samples an indication that the humid atmosphere was favourable to them. Gradually the fungi spores became very visible to the naked eyes. The cellulose components of the three samples were broken down by the fungi for food leaving a brown - dark residue of lignin thus leading to weakening of the samples before decay was visible accompanied by a rapid decrease in weight of the samples. Samples D and E were oven dried for 6hours using laboratory controlled temperature of 1050C. At the end of the 6 hours the weight of D and E which were initially 20.32gm and 19.98gm were reduced to 17.62gm and 17.68gm respectively. The percentage moisture content (% M. C) of sample D and E were found to be 15.88% and 13.01% respectively. This two samples were further treated with a chemical creosote and left in the same humid atmosphere as A, B and C for 60days. At the end of the 60th day, it was observed that both sample D and E were not attacked by any fungi. This research result of our experimental analysis helps to recommend that before using Alstonia boonei for light construction works; it should be properly and adequately dried below the moisture content that does not allow for the operation of their fungi that is the moisture content should be less than 19% for air dried wood and 15% or less for oven dried wood. The wood should be properly treated with chemical e.g. Creosote that dislodges the activities of this fungi.